The present invention relates in general to grinding elements for pulverizers and in particular to a new and useful design for a tire used in a roll wheel assembly for a pulverizer which increases the wear life of the tire.
Pulverizers are commonly used to grind various materials in the coal processing, ceramic, and chemical industries. A roll and race pulverizer uses grinding elements comprising a plurality of roll wheel assemblies or tires suspended from driving arms and which rotate around their respective axes of rotation through contact against a grinding ring or race for grinding and reducing the size of the incoming material, particularly coal. Each grinding element or roll wheel assembly uses a replaceable outer tire. Currently, the replaceable outer tires used in the roll wheel assemblies are manufactured from alloy as a casting and are symmetrical about a radial center plane.
Despite the symmetrical orientation of the replaceable outer tires of the roll wheel assemblies, the tires wear unevenly during normal pulverizer operation. The problem with uneven wear can be resolved by rotation; i.e., a side-to side reversal of the partly worn tire comprising each roll wheel assembly. However, to perform this operation the pulverizer has to be stopped and taken out of service for a significant period of time. The task of pulverizer tire rotation requires removal of the entire roll wheel assembly from the pulverizer through an access door. This is a difficult and labor intensive operation; special equipment is required because each roll assembly can weigh as much as 35,000 pounds. Once removed from the pulverizer, the tires must be disassembled from the roll wheel assemblies by performing a heating operation. This raises the possibility of local overheating and resultant cracking, which will ruin the tire and require it to be repaired, if possible, or replaced. Additionally, only a slight improvement in useful tire life is achieved through this tire rotation procedure, and it is generally not enough to justify the costs involved.
Thus a need exists for an improved pulverizer tire for a roll wheel assembly that can provide increased wear life at minimal additional cost.